Diversity and specificity of mycorrhizal fungi associated with Epidendrum secundum (Orchidaceae) in campo de altitude at State Park of Serra do Brigadeiro MG / Diversidade e especificidade de fungos micorrízicos associados a Epidendrum secundum (Orchidaceae) em um campo de altitude no Parque Estadual da Serra do Brigadeiro MG

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

In nature, species of Orchidaceae are always associated with mycorrhizal fungi. However, diversity of fungi associated to the orchids is little studied. Fungus-plant specificity has been observed and its comprehension is very important to establish programs for the simbiotic propagation of orchids. The objective of this work was to study the diversity and specificity of Rhizoctonia-like fungi associated to four populations of Epidendrum secundum, growing at three localities in the Totem Deitado Mountain, at State Park of Serra do Brigadeiro, in Minas Gerais. Segments of healthy roots were collected from two populations growing at campo garminóide, near rocky outcrop, and another one growing at campo garminóide by a escrube area, localized at 1700 m above the sea level, and the last was growing at campo graminóide on a rocky outcrop, localized at 1580 m of altitude. Twenty six isolates, all belonging to the Epulorhiza, were obtained by transferring cortical root fragments to the isolation medium. In general, the colony aspect of the isolates, the morphology, and width of monilioid cells were different among isolates from different localities, but similar in the population. The multivariate analyses of morphological characteristics using Tocher optimization, UPGMA, and graphic dispersion by canonic variables, separated the 26 isolates in, respectively, six, two, and three groups, showing similarities among most of all isolates from population I, II, and IV, and, also, among isolates from population III, and M61, from population II. Epulorhiza spp., isolated from E. secundum, supported seed germination of this plant species, but efficiency to promote protocorm development varied even among the isolates that presented morphological similarities. Results from this work show that there is high diversity of mycorrhizal fungi in Epulorhiza associated to E. secundum in this region and confirm the high specificity of this orchid to this fungal genus.

ASSUNTO(S)

orquídea epulorhiza epulorhiza rhizoctonia orchid microbiologia e bioquimica do solo simbiotic germination germinação simbiótica rizoctonióides

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